<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>BaOsO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>: A Hund's metal in the presence of strong spin-orbit coupling
Max Bramberger, Jernej Mravlje, M. Grundner, Ulrich Schollwöck, Manuel Zingl
Abstract
We investigate the $5d$ transition metal oxide ${\mathrm{BaOsO}}_{3}$ within a combination of density functional theory and dynamical mean-field theory, using a matrix-product-state impurity solver. ${\mathrm{BaOsO}}_{3}$ has four electrons in the ${t}_{2g}$ shell akin to ruthenates but stronger spin-orbit coupling (SOC) and is thus expected to reveal an interplay of Hund's metal behavior with SOC. We explore the paramagnetic phase diagram as a function of SOC and Hubbard interaction strengths, identifying metallic, band (van Vleck) insulating, and Mott insulating regions. At the physical values of the two couplings, we find that ${\mathrm{BaOsO}}_{3}$ is still situated inside the metallic region and has a moderate quasiparticle renormalization ${m}^{*}/m\ensuremath{\approx}2$, consistent with specific heat measurements. SOC leads to a splitting of a van Hove singularity close to the Fermi energy and a subsequent reduction of electronic correlations (found in the vanishing SOC case), but the SOC strength is insufficient to push the material into an insulating van Vleck regime. In spite of the strong effect of SOC, ${\mathrm{BaOsO}}_{3}$ can be best pictured as a moderately correlated Hund's metal.